1. Technical Field
This invention relates to the field of telephony and, more particularly, to providing telephony services to subscribers.
2. Description of the Related Art
The delivery of most telephony services and features is tied to the directory number of a calling party or a called party. In fact, nearly all of the activities performed by a conventional telephony system, whether a circuit-switched telephone network such as the public switched telephone network (PSTN) or a packet-switched telephony system, are based on such directory numbers or network addresses as may be the case. The dialed directory number can be referred to as the DNIS in reference to directory number identification service, a service which identifies for a receiving party the number dialed by a calling party. The directory number of the calling party can be referred to as an ANI in reference to automatic number identification, the service which provides the receiving party with the directory number of the calling party.
When a calling party initiates a call to a receiving party, the DNIS and the ANI can be used to authenticate the call. Authentication can include tasks such as finding the ANI in a list of authorized subscribers and ensuring that the DNIS is valid. Taking another example, the switching of calls to and from a subscriber also can be achieved through the use of the subscriber's directory number. That is, if a calling party places a call to a receiving party, the call can be routed to the receiving party based on an area code and/or an exchange code of the DNIS.
The reliance of conventional telephony systems on the DNIS and ANI not only determines how features and services are to be implemented and delivered, but also dictates the mode of operation of other portions of the telephony system. In consequence, services provided by conventional telephony systems are tightly linked to the DNIS and ANI. For example, billing, interactive voice response functions, call routing, call authentication, and subscriber information retrieval are predicated upon the DNIS and the ANI.
Given the mobile nature of today's society, however, providing subscribers with telephony services according to the DNIS and/or the ANI can have disadvantages. For example, as a subscriber moves from one location to another, the subscriber may utilize telephony equipment associated with a directory number and account that is different from that of the “mobile” subscriber. As a result, the subscriber can be blocked from accessing particular telephony services which typically are available to the subscriber when calling from a home or another number used by that subscriber. Moreover, if a subscriber does access one or more telephony services from a different number, for example while traveling, the account associated with the number from which the subscriber has called typically is billed rather than the subscriber.